Railway track circuits



Filed April 20. 1929 Flcshl.

1 way 5 INVENT BY Kym TTOIIQNEY for various usual controls.

Patented Mar. 31, 1931 'UNITED STATES PATENT oFFrcs WINTHROIP K. HOWE, OF ROCHESTER, NEW YCEK, ASSIGN'OB TO GENERAL RAILWAY SIGNAL COMPANY, OF ROCHESTER, NEW YORK RAILWAY TRACK CIRCUITS Application filed April 20,

ably the exit end, a track battery or other source of electrical energy, and across the other end, preferably the entrance end, a track relay, whereby, on occupancy of the section, the shunting efiect of the wheels and axles of the occupying train causes the relay to release.

In circumstances such as outlined above, it is clear that changes in ballast resistance, or in other words changes in ballast leakage, will change the current normally flowing through the track relay so that, if adjusted to release when shunted by a train, under one condition of ballast resistance it is possible that under other conditions of ballast resistance, the shunt will be less effective to cause release of the relay.

Further objects, purposes and characteristic features of the invention will appear as the description progresses, reference being had to the accompanying drawing showing, solely by way of example, and not in any manner in a limiting sense, two form which the invention can assume.

In the drawings Fig. 1 is a diagrammatic view showing one form of the invention.

Fig. 2 is a diagrammatic view showing a second form of the invention.

Referring now to the drawing, there are shown two track rails 1 constituting a stretch of single track divided by insulating joints 2 into a usual signal block. Across the exit end of the block, the direction of trafiic being in the direction of the arrow, is connected a track battery 3 or other source of elec- I trical energy. in series with a current limiting resistance l, and across the other, or entrance, end of the block is connected a track relay 5 having contact fingers 6 etc.

1929. Serial No. 356,716.

In series with the track relay, and connected between the relay and one of the track rails, is a control electromagnet or relay CR, having a heavy copper ring 7, or other means, on its core,'for making it slow acting. Relay CR has an armature 9 connected for operating on a carbon pile or other type variable resistor 10, whereby the resistance through the carbon pile is increased when the current through the control relay winding increases,

and vice versa.

YVith the construction above described, it is apparent that when the ballast resistance lncreases, or in other words, when the ballast leakage decreases, the voltage across the track relay increases, and more current will tend to flow through the track relay than when the ballast resistance is less. Thisresults in causing the armature-9 to increase the resistance through the carbon pile whereby the increased voltage across the track relay cannot increase the current flowing through the relay any substantial amount above the normal amount.

lVhen ballast conditions change so as to decrease the ballast resistance, that is, to increase the ballast-leakage, the voltage across the track relay decreases, tending to decrease the current in the control relay winding, so

as to decrease the resistance in the track re-' lay circuit, whereby to prevent the current 1 through the track relay from decreasing any substantial amount below normal.

The advantageof this control can be read.- ily appreciated, when considering the operation in the usual arrangement of parts, without any automatic correction for variation in ballast resistance. With a ballast resistance of, for example, 4 ohms, corresponding to wet weather conditions, andfa battery volt-- age across the track rails of165 volts, a 4 ohm track relay will normally be energized by a current of about .070 amperes to pick it up and maintain it up. On being shunted out by occupancy of its block, the current through the track relay will decrease to about .030 amperes to cause the relay to release.

. If the ballast resistancenow increases, due for example to more favorable weather conditions, or for any other reason, tor-each, for

example, 12 ohms, than the normal current traversing the track relay may be about .100 amperes, so that on being shunted by occupancy of its block, the current through the relay might be, at the least, about .050 amperes, that is, a high enough current value to maintain the relay up, even though its block be occupied.

In other words, with a change in ballast resistance such as can readily occur in actual practice, due, for example, to a change from wet to dry weather, proper shunting action, which occurs under low ballast resistance conditions, is prevented from occurring under high ballast resistance conditions.

The arrangement shown in Fig. 1, and described above, operates to prevent the normal current through the track relay from increasing when the ballast resistance increases and thereby insures that proper shunting of the relay shall occur, regardless of variations in ballast resistance.

It is obvious that if the track relay as usually connected, be arranged to be properly picked up and held up when unshunted, under dry weather conditions, corresponding to high ballast resistance, then under low ballast resistance conditions the relay might release even though the block be unoccupied. The present invention, however, effectually prevents this.

The control relay is made slow acting, as above described, so as not to respond immediately to the shunting effect of occupancy of the block, since, if it were fast acting, upon occupancy of the block, the control relay might operate to so decrease the resistance oi the carbon pile as to prevent the relay current falling to drop away value.

In Figure 2 is shown, a second form of the invention, in which the track rails 1 insulating joints 2 battery 3 and limiting resistance 4 and track relay 5, are arranged the same as in Fig. 1.

In this form, however, instead of having means for automatically varying the pressure on a carbon pile resistor, a ballast lamp BL is employed, constituted, for example, by an evacuated bulb 11, in which is an iron filament 12, whereby, as the current through the track relay increases, the temperature of the filament 12 increases to thus increase the resistance in circuit with the track relay and so cut down the flow of current. It current flow tends to decrease, the reverse operation takes place. Thus, this device operates to maintain the current flowing through the track relay, under unshunted conditions, at a substantially constant value. Y

The ballast lamp BL is encased in a heat insulating casing 13, whereby to give it slow acting characteristics, in the same manner as described above in connection with Fig. 1, and for the same reasons.

It is thus clear that this inventien pro-vices means for automatically maintaining the current normally following through a track relay in a track circuit, under unshunted conditions, at substantially its normal value, regardless of ballast resistance, to thus insure proper operation of the relay when shunted and unshunted, regardless of changes in ballast resistance.

The above rather specific description of one form of device embodying the present invention, has been given solely by Way of illustration, and is not intended, in any manner whatsoever, in a limiting sense. Obviously, this ini' en-tion can assume many different physical forms, and is susceptible of numerous modifications, and all such forms and modifications are included by this invention, as come within the scope of the appended claims.

Having described my invention, I now claim 1. In a track circuit, in combination with an insulated stretch of track, a source of electrical energy connected across one end of the track, and a track relay connected across the other end of the track; electro-magnetic regulating means connected in series with the track relay for automatically maintaining the normal energizing current through the track relay constant regardless of variations in inter-rail potential at the relay end of the track, by increasing or decreasing the resistance to current flow through the track relay according as the said potential increases or decreases, respectively.

2. In a track circuit, in combination with an insulated stretch of track, a source of electrical energy connected across one end of the track, and a track relay connected across the other end of the track; regulating means for automatically maintaining the unshunted energizing current through the track relay constant regardless of variations in ballast resistance, said regulating means including a variable resistance in series with the track relay to the track, and a relay to control said resistance and variably energized in accordance with ballast resistance.

3. In a track circuit, in combination with an insulated stretch of track, a source of electrical energy connected across one end of the track, and a track relay connected across the other end of the track, electro-magnetic regulating means for automatically maintaining the normal energizing current through the track relay constant regardless of variations in ballast resistance, said regulating means including a variable resistance in series with the track relay to the track,

and a slow-acting relay to control said resistance and variably energized in accordance with ballast resistance.

4. In atrack circuit, in combination with an insulated stretch of track, a source of electrical energy connected across one end of the track, and a track relay connected across the other end of the track, regulating means for automatically maintaining the normal energizing current through the track relay substantially constant regardless of variations in ballast resistance, said regulating means being connected in series between the track relay and a track rail and including a carbon pile resistor and a control relay which is variably energized in accordance with ballast resistance, for Varying pressure on the resistor.

5. In a track circuit, in combination with an insulated stretch of track, a source of electrical energy connected across one end of the track, and a track relay connected across the other end of the track; electro-magnetic regulating means for automatically maintaining the normal energizing current through the track relay constant regardless of variations, in ballast resistance, said regulating means being connected in series between the track relay and a track rail and including a carbon pile resistor and a slow acting control relay, which relay is variably energized, in accordance with ballast resistance for varying pressure on the resistor.

6. In a track circuit, in combination with an insulated stretch of track, a source of electrical energy connected across one end of the track, and a track relay connected across the other end of the track; regulating means for automatically maintaining the normal energizing current through the track relay constant regardless of variations in ballast resistance, said regulating means being connected in series between the track relay and a track rail and including, a carbon pile resistor, and a control relay variably energized in accordance with ballast resistance for varying pressure on the resistor, said control relay including means making it slow to respond to changes of voltage applied thereto.

In testimony whereof I aflix my signature.

IVINTHROP K. HOWE. 

